How do off market deals work?

[Diego Amezquita]

hello BP members, I have one year in real-estate and so far I have acquired 2 properties from a wholesaler through my real estate agent I am located in Houston Texas. lately I want to go off market and send mailers do some door knocking but the truth is that I don't know how to get started when it comes to the paper work. For example, if a potential seller is interested in selling, what paperwork do I need to get the process started. If I am not wrong I need a purchase agreement but once that is filled and signed whats next? does anyone have and resources like books, website, or bp post about this? or can anyone share their knowledge on this? anything would really help!! I will keep going through google to see if I can find any good info on the topic.